Field of the Invention
The present invention relates to a driving apparatus used in an optical device or the like, more specifically, to a driving apparatus provided with a vibration wave motor.
Description of the Related Art
Conventionally, there have been vibration wave motors as examples of this type of driving apparatus. In the vibration wave motors, there has been conventionally known a technique for driving a sliding member relatively by bringing a vibrator, which vibrates periodically by application of a high-frequency voltage thereto, into pressed contact with a friction member. Further, there has been known a technique for generating a greater drive force by using a plurality of vibrators to drive a driving portion, in a case where a weight of driving portion is heavy, and the like.
The above mentioned prior art disclosed in Japanese Patent application Laid-Open No. 2006-067712 is configured in such a manner that vibrators are placed in both upper and lower sides of a friction member and power is transmitted to a lens mirror barrel that is desired to be driven, through a pin for extracting a drive force from end portions of the vibrators.
However, according to the above-mentioned configuration, a positional deviation between a portion (frictional contact surface of the vibrators) generating a drive force and an extracting portion of the drive force becomes large. When a position of the extracting portion of the drive force is away from the frictional contact surface of the vibrator, moment is generated on the vibrators due to a weight of a driven object (lens). Then, a frictional contact state of the vibrators is changed. Therefore, drive becomes unstable so that a stable drive force is hardly extracted.